The present application relates to the transference of information over an airgap separating a receiver from a transmitter. It finds particular application in the context of computed tomography (CT) imaging modalities, which may be utilized in medical, security, and/or industrial applications, for example, where at least one of the transmitter and the receiver is located on a rotating gantry and an airgap separating a transmitting antenna from a receiving antenna is small (e.g., 20 mm or less). However, it may also apply to other applications, such as explosive detection machines, radar antennas, etc. where communication signals are wirelessly transferred between a transmitter and a receiver.
Today, CT and other radiation imaging modalities (e.g., single-photon emission computed tomography (SPECT), mammography, projection radiography, etc.) are useful to provide information, or images, of interior aspects of an object under examination. Generally, the object is exposed to radiation comprising photons (e.g., such as x-rays, gamma rays, etc.), and an image(s) is formed based upon the radiation absorbed and/or attenuated by the interior aspects of the object, or rather an amount of photons that is able to pass through the object. Generally, highly dense aspects of the object absorb and/or attenuate more radiation than less dense aspects, and thus an aspect having a higher density, such as a bone or metal, for example, will be apparent when surrounded by less dense aspects, such as muscle or clothing.
Some radiation imaging modalities, such as CT, are configured to generate volumetric data corresponding to an object under examination. To generate this volumetric data, the CT imaging modality is typically configured to rotate a radiation source and detector array about the object under examination (e.g., causing the object to be viewed from a plurality of angles). For example, the radiation source and/or detector array may be mounted to a rotating gantry (at times referred to as a rotor) configured for rotation relative to a stationary unit (at times referred to as a stator) configured to support the rotating gantry.
Given that the radiation source and detector array are mounted on the rotating gantry, power and control information (e.g., instructing the radiation source and/or other electronic components how to operate) are typically supplied to the rotating gantry from the stationary unit. Moreover, imaging data (e.g., data generated in response to the detection of radiation by the detector array) is typically transferred from the rotating gantry to the stationary unit (e.g., for further processing and/or to be displayed to security/medical personnel). It may be appreciated that the volume of data transferred, particularly with respect imaging data, may be quite large. For example, some imaging modalities may require transfer speeds of up to 5 gigabits per second (e.g., particularly if the rotating gantry does not comprise a storage medium to temporarily store data until it can be transferred).
Conventionally, slip-ring assemblies have been used to transfer power and/or information (e.g., control information and/or imaging data) between the stationary unit and the rotating gantry or more generally between a movable unit and a stationary unit (or between two movable units) through the physical contact of two materials (e.g., via a sliding contact). For example, a slip-ring attached to the stationary member may comprise metal brushes that are configured to physically contact electrically conductive surfaces (e.g., metal brushes) comprised on a slip-ring attached to the movable unit, allowing power and/or information to be transferred between the stationary unit and the movable unit.
While the use of slip-ring assemblies has proven effective for transferring power and/or information between a stationary unit and a movable unit (e.g., such as a rotating gantry) and/or between two movable units, conventional slip-ring assemblies may generate dust or particles (e.g., as metal brushes wear), may be unreliable (e.g., again as contact surfaces, such as metal brushes, wear), and/or may be noisy (e.g., as surfaces rub against one another), which may cause interference with some procedures (e.g., CT imaging). Other drawbacks of slip-ring assemblies may include cost and complexity of manufacture due to special materials and/or mechanical precision that may be required.
More recently, contactless assemblies have been devised to transfer the data (e.g., or electrical signals derived from the data) between the rotating gantry and the stationary unit. For example, U.S. Pat. No. 5,577,026 (assigned to Analogic Corporation) and U.S. Pat. No. 7,760,851 (assigned to Siemens Aktiengesellschaft and Schleifring and Apparatebau GmbH), at least some of which are respectively incorporated herein by reference, describe two different approaches to contactless assemblies for transferring data. While such assemblies overcome many of the aforementioned drawbacks to a slip-ring assembly, the amount of data capable of being transferred via the foregoing contactless assemblies is limited. For example, U.S. Pat. No. 7,760,851 appears to describe transferring data at a transfer speed of, at most, 1.5 Gbps. As radiation imaging modalities continue to develop (e.g., and transition to photon counting imaging modalities), data may be required to be transferred at much faster speeds. Further, data may be required to be transferred at a wider range of frequencies than either of the aforementioned contactless assemblies is configured to handle.